Conditions for Setting the DTC
WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
Each controller on the CAN serial data circuit monitors the activity or traffic on the bus. The modules have prerecorded information about what messages should be expected during normal functionality. The module setting the DTC does not receive CAN messages from all of the modules it expected to, or receives too many CAN messages. This indicates that there may be fewer controllers or more controllers actively communicating on the bus than programmed.